Scoliosis is a spinal deformity characterized by an abnormal curvature of the spine in the coronal plane. Adolescent idiopathic scoliosis (AIS) is the most prevalent type of scoliosis which develops during adolescence in an otherwise healthy patient and typically ceases at the onset of skeletal maturity. The cause of the disease is presently unknown.
Current surgical treatment of scoliosis involves manipulation of the spinal column and attachment of corrective devices for fusion of a portion of the spine. One such system, the Cotel-Dubousset system utilizes rigid metal rods attached to the spine. The rods are manipulated during surgery in an attempt to reduce abnormal curvatures and rotations of the spinal column. Large loads are exerted on the spine for correction which risks the patient's neurological condition. Recovery from these procedures can be lengthy and painful. Also, if normal lordosis and kyphosis are not restored, a condition called “flat back syndrome” may occur causing chronic pain. Even a successful procedure rarely results in a normal spinal curvature and the patient is left with an immobile spinal section. The discs above and below the fusion zone are at risk of future degeneration due to the increased mechanical demands placed on them.
It is therefore evident that there are flaws in prior art methods and devices. Most prior art devices are part of the load path of the spinal column. For example, it is understood that the Cotel-Dubgousset system rigidly attaches stiff metal rods to the spine. A structure having two roughly parallel support members relies primarily on the stiffer of the two members for transmission of loads. Therefore, loads exerted on an instrumented spine are transferred through the implant instead of through the spine. Spinal loads can be significantly large, and the implants will not support such loads indefinitely. Fatigue failure of the implant will occur if fusion is delayed.
Therefore, there is an unaddressed need that exists to provide a new and better system for correcting spinal deformities.